Fast food stores typically display the names of food items and prices on signs which are provided with back lighting. The prices are displayed on modules permitting changing the price. Typically, the numbers are on pre-coiled price strips which are supported so that when one of the numbers is displayed at an aperture in a bezel, the coils at each end of the strip are theoretically spread apart behind the displayed number to permit light to enter from the light source. In practice, however, those coils tend to close behind the displayed number and cast shadows on the number. Thus, the lighting is not uniform and the displayed numbers are darker than desirable.
A further problem encountered with pre-coiled price strips is that the nature of the strip dictates that the larger of coils tends to take up the smaller coil, i.e. when the displayed number is not exactly in the middle of the strip, the larger coil will exert a greater force than the force exerted by the smaller of the two coils. Therefore, the displayed number tends to migrate towards the larger coil and change the displayed price. This tendency increases as the sign is subjected to vibration by wind, ventilating fans, etc.